Science Box

Be honest - don’t you cut corners on sleep too? Whether it’s late-night studying, binge-watching, or endless scrolling, sleep often gets demoted to something that would be “nice-to-have” rather than a biological priority. But the truth is, sleep is not optional - it’s essential. It may seem like it’s a passive shutdown period for your body, but it’s actually one of the most active and dynamic states that your body enters everyday.

At the heart of sleep biology lies our circadian rhythm - a 24-hour internal clock which is regulated by the brain’s suprachiasmatic nucleus (SCN), located in the hypothalamus. This rhythm controls when we feel alert, as well as when we feel sleepy, responding mainly to light and darkness.
When it gets dark, our SCN signals the pineal gland to release melatonin, which is also known as the “sleep hormone”. In contrast, morning light stops melatonin production and promotes wakefulness. This delicate feedback loop helps align our sleep-wake cycle with the environment.
However, some people have problems with their sleep/wake cycle, meaning that their brain does not keep them awake or asleep at appropriate times. This can show up in different sleep disorders. For example, insomnia occurs when people have trouble falling asleep, staying asleep, or both - so people either get little sleep or a lower quality of sleep. Narcolepsy, on the other hand, causes periods of extreme daytime sleeping and can also lead to muscle weakness, which can severely affect day-to-day life.
In other cases, the problem isn’t a disorder, but is simply a misalignment between our circadian clock and our actual schedule. This could be due to jet lag, which is when people face trouble adjusting their sleep to a new time zone after long distance travel, but it can be resolved within a few days. It could also be a cause of shift work disorder, which occurs when people who work at night may face issues sleeping during the day.

Sleep is further divided into REM (Rapid Eye Movement) and Non-REM stages. Both play a different but equally critical role:
Non-REM sleep is essential for physical restoration - tissue repair, immune system support, and muscle recovery all take place in these stages of sleep, usually early in the night.
REM sleep, on the other hand, is when our eyes twitch and our brain is active. Brain activity measured in REM sleep is extremely similar to our brain activity when we’re awake as this is the stage where dreaming usually occurs. We usually have more REM sleep later in the night, but not so much in colder temperatures as during this stage, our body does not regulate its temperature properly.
Throughout the night, we cycle through these stages about 4-6 times, and disruption to this cycle can impact everything from our mood and focus to our hormonal balance and metabolism.
In fact, newborns spend more time in REM sleep whereas Non-REM sleep peaks in childhood. Non-REM sleep also falls in our teenage years and continues to decrease as we age into adulthood.

Sleep, just like everything in our body, is also driven by a balance of chemicals and neurotransmitters:

Adenosine, a byproduct of cellular activity, builds up in the brain during the day and creates “sleep pressure” - so the longer we’re awake, the more adenosine accumulates, and the sleepier we feel!
Melatonin, as mentioned before, is released in the darkness, and signals the body to prepare for sleep.
Neurotransmitters such as GABA help slow brain activity, while serotonin and acetylcholine play roles in REM sleep regulation.

This complex connection between so many molecules is what makes sleep a biologically rich and necessary process. Sleep isn’t you being lazy - it’s simply biochemistry!

So what happens if we don’t get proper sleep?
Chronic sleep deprivation doesn’t just make you tired. It has measurable effects on almost every system in the body:

Brain health: Impaired memory, poor concentration, increased risk of anxiety and depression.
Immune system: Reduced ability to fight off infections.
Metabolism: Increased risk of obesity and type 2 diabetes.
Cardiovascular health: Higher risk of heart disease and hypertension.

Long-term, poor sleep has even been linked to neurodegenerative diseases such as Alzheimer’s, as the brain uses deep sleep to flush out harmful waste products like beta-amyloid.

Have we been convinced to stop sacrificing sleep now?
Most adults need 7-9 hours of sleep per night. However, teenagers may need more such as 8-10 hours, due to developmental changes.
Although, quality matters just as much as quantity! Fragmented sleep, late-night light exposure, and irregular sleep schedules can all impact how restorative our sleep is - even if you hit that 8-hour mark.

Therefore, sleep isn’t “doing nothing” for us. It’s our body’s nightly tune-up, cleaning, repairing, and strengthening systems from head to toe. Understanding the biology of rest reminds us that sleep isn’t a luxury - it’s a necessity.
So the next time you’re tempted to stay up late, ask yourself: is that extra hour really worth compromising something as powerful as sleep?
Because at the end of the day (literally), rest isn’t weakness - it’s simply science!

Sources:

Author: Saisha Arora

Why Do We Need Sleep? The Biology of Rest